7-1 Investigate & Fix Special Causes The Quality Improvement Model Use SPC to Maintain Current Process Collect & Interpret Data Select Measures Define.

7-1

Investigate & Fix Special Causes


TheQualityImprovementModel

Use SPC to Maintain Current Process

Collect & Interpret

Data

Select Measures

Define Process

IsProcessCapable

?

Improve Process

Capability

IsProcessStable

?



No

Yes

No

Yes


Purpose:•Assure stability of the

measures.•Establish permanency of

solutions to recurring special causes.

•Improve procedures and training.

7-2



Unstable Process

Time

Quality Characteristic

Control Chart

UCL

CL

LCL

How do we improve an unstable process?

7-3



Potential Special Causes

Lack of standardization Lack of consistent process conditions

Uncontrolled process variables Unknown process variables Fluctuating business environment Equipment malfunctions

Unstable measurement process

Changes in process inputs

7-4



The Improvement Process

Study the Symptoms Theorize Causes Establish True

Causes

Propose Alternative Solutions

Select & Apply Solution

Maintain Improvements

We must take the time to identify the cause before attempting to solve the problem.

Diagnose Solve

7-5



Special Cause Action Plan(S.C.A.P.)

A planned sequence of activities for investigating and taking action on a problem which has been detected.

Provides a prioritized listing of potential special causes. The S.C.A.P. should be updated whenever necessary.

Actions1) Investigation2) Compensation 3) Documentation4) Correction5) Prevention

Note: This is the most important part in implementing S.P.C.

7-6



Investigative Action

Systematic “detective” work to determine the root source of the special cause. The investigative actions should be directed toward determining:

What When Why Where

Unless the urgency of special cause dictates other action, investigative action should precede any other actions. Regardless of the urgency, investigative action should always be taken at some point.

Note: This is the most important part of the S.C.A.P..

7-7


Investigate & Fix Special CausesCompensating Action

Adjustment made to the process after a nonconformity, defect, or other undesirable process situation in an attempt to restore the process to the desired state, without addressing the underlying cause of the situation. (ISO definition)

• Taking action on the process in the form of adjustments to the process. These actions do not remove the cause but are known to adjust the process in a favorable direction. (Adjusting)

OR

• Taking action on the process to remove the symptom of the special cause. This may not prevent the same problem from recurring in the future. (Fixing)

Adjustments may help one part of the process but could be detrimental to others.

7-8



Documentation

Recording the suspected cause of the problem, what actions were taken and how effective the action was.

Benefits:•

•

•

•

7-9



Cause D

Cause G

CauseA

Cause B

Cause N All others

Frequency of Occurrence

Pareto of Causes

Note: Putting resources to eliminating Cause D will result in most significantImpact on process improvement.

7-10



Corrective Action

Actions taken to eliminate the causes of existing nonconformity, defect, or other undesirable situation in order to prevent recurrence (ISO definition).

• Permanent removal of the root source of recurring special causes that have been identified.

Focus is on preventing major recurring special causes.

Implementation results in variability reduction.

7-11



Preventive Action

Action taken to eliminate the causes of a potential nonconformity, defect, or other undesirable situation in order to prevent occurrence.(ISO definition)

• Permanent removal of the root source of a potential special cause that could affect the process.

May involve using learning's from one process on another process where the special cause might also occur.

7-12



•A standard way to perform a task.

•A standard range that a key process variable should be within.

•Standards should be audited.

Control To A Standard

Note: S.O.P.'s NOT being followed can be a major reason for instabilities on control charts!

7-13



• Control "Charts" will NOT improve the process!

•S.C.A.P's IMPROVE the process

•Provide a procedure for operations to follow in identifying and removing the special cause symptom.

• Promote a standardized approach to investigating and compensating for special causes.

• Provide a vehicle for documenting causes found and actions taken to aid in future problem solving.

Why S.C.A.P.'s?

7-14



Rating of Importance to

Customer10 1 9 9 5 8

1 2 3 4 5 7

Bre

ak %

Mel

t T

emp

Bot

tle O

utpu

t

Cla

rity

Wei

ght

Wal

l V

aria

tion

Total

Process Step Process Input

Melt Resin Resin 9 9 3 9 9 9 324Blow Bottle Mold Design 9 0 9 9 0 9 324

Extrude Parison Programing 3 3 9 0 9 9 231Extrude Parison Die Tip Temp 3 3 3 9 3 9 228

Blow BottleMold Water Temp

9 0 9 3 0 0 198

Blow BottleWater Volume/Cooling Rate

9 0 9 3 0 0 198

Extrude Parison Head Design 3 9 3 3 3 9 180Extrude Parison Tooling 3 3 3 3 3 9 174

Blow Bottle Pinch Design 9 0 9 0 0 0 171Melt Resin Barrell Temp 3 9 9 1 3 3 168Melt Resin Screw Speed 3 9 9 1 3 3 168Melt Resin Screw Design 3 9 9 1 1 1 142

Blow Bottle# of Mold Cooling Zones

9 0 3 0 0 0 117

Tail DetabTime from extraction to Detab

9 0 3 0 0 0 117

Remember The C&E Matrix

Note: C&E is a good place to start building control strategies. This information will be used to develop a Failure Modes Effect Analysis (FMEA) …

7-15



A structured approach to:A structured approach to: Assist in developing SCAP's identifying the ways in which a product or process

can fail estimating the risk associated with specific causes

prioritizing the actions that should be taken to

reduce the risk evaluating the design validation plan (product) or

the current control plan (process)

Primary DirectivePrimary Directive:: Identify ways the product or process can fail and eliminate or reduce the risk of failure

FMEA Definition

7-16



Key tool of process team to improve the process in a preemptivepreemptive manner (before failures occur)

Used to prioritizeprioritize resources to insure process improvement efforts are beneficial to customer

Used to documentdocument completion of projects

Should be a dynamicdynamic document, continually reviewed, amended, updated

Role of FMEA

7-17



AnalyzesAnalyzes new processes

IdentifiesIdentifies deficiencies in the process control plan

EstablishesEstablishes the priority of actions

EvaluatesEvaluates the risk of process changes

IdentifiesIdentifies potential variables to consider in Exploratory Data Analyses (EDA) and Design of Experiments (DOE) studies

GuidesGuides the development of new processes

HelpsHelps set the stage for breakthrough

Purposes of FMEA

7-18


Investigate & Fix Special CausesFMEA Inputs and Outputs

InputsInputs Process map C&E matrix Process history Process technical procedures

OutputsOutputs List of actions to prevent causes or to detect

failure modes History of actions taken

7-19


Investigate & Fix Special CausesFMEA Team

Team approach is necessary

Recommended representatives: Design Practitioners / Operators / Supervisors Quality Reliability Maintenance Materials Testing Supplier

7-20



Failure Mode

Effect

Cause

Current Controls

Severity, Occurrence, Detection

Risk Priority Number (RPN)

FMEA Terms

Next, Going to define each of these terms…

7-21


Investigate & Fix Special CausesFailure Mode - Definition

Failure ModeFailure Mode - the way in which a specific process input fails - if not detected and either corrected or removed, will cause the effect to occur

Can be associated with a defect (in discrete manufacturing) or a process input variable that goes outside of specification

o Anything that an operator can see that’s wrong is considered a failure mode

ExamplesExampleso Incorrect PO number

o Sample Size too small

o Dropped call (customer service)

o Temperature too high

o Surface contamination

o Paint too thin

7-22


Investigate & Fix Special CausesEffect - Definition

EffectEffect - impact on customer requirements Generally external customer focus, but can also include

downstream processes

ExamplesExamples Incorrect PO number: Accounts receivable traceability

errors Dropped call: Customer dissatisfaction Temperature too high: Paint cracks Surface contamination: Poor adhesion Paint too thin: Poor coverage

7-23


Investigate & Fix Special CausesCause - Definition

CauseCause Sources of process variation that causes the failure mode to

occur Identification of causes should start with failure modes

associated with the highest severity ratings

ExamplesExamples Incorrect PO number: Typographical error Dropped call: Insufficient number of CS representatives Temperature too high: Thermocouple out of calibration Surface contamination: Overhead hoist systems Paint too thin: High solvent content

7-24


Investigate & Fix Special CausesCurrent Controls - Definition

Current ControlsCurrent Controls Systematized methods/devices in place to prevent or

detect failure modes or causes (before causing effects)

Prevention consists of mistake proofing, automated control and set-up verifications

Controls consist of audits, checklists, inspection, laboratory testing, training, SOP’s, preventive maintenance, etc.

7-25


Investigate & Fix Special CausesRisk Priority Number (RPN)

The output of an FMEA is the Risk Priority Number The RPN is a calculated number based on

information you provide regarding

o the potential failure modes,

o the effects, and

o the current ability of the process to detect the failures before reaching the customer

It is calculated as the product of three quantitative ratings, each one related to the effects, causes, and controls:

EffectsEffects CausesCauses ControlsControls

RPN = Severity X Occurrence X Detection

7-26


Investigate & Fix Special CausesDefinition of RPN Terms

Severity (of Effect)-Severity (of Effect)- importance of effect on customer requirements - could also be concerned with safety and other risks if failure occurs (1=Not Severe, 10=Very Severe)

Occurrence (of Cause)-Occurrence (of Cause)- frequency with which a given cause occurs and creates a failure mode. Can sometimes refer to the frequency of a failure mode (1=Not Likely, 10=Very Likely)

Detection (capability of Current Controls) -Detection (capability of Current Controls) - ability of current control scheme to detect or prevent: the causes before creating failure mode the failure modes before causing effect 1=Likely to Detect, 10=Not Likely at all to Detect

7-27


Investigate & Fix Special Causes"Example" Rating Scale

Rating Severity of Effect Likelihood of Occurrence Ability to Detect

10 Hazardous without warningVery high:

Can not detect

9 Hazardous with warningFailure is almost inevitable

Very remote chance of detection

8 Loss of primary functionHigh:

Remote chance of detection

7Reduced primary function

performance

Repeated failuresVery low chance of detection

6 Loss of secondary functionModerate:

Low chance of detection

5Reduced secondary function

performance

Occasional failuresModerate chance of detection

4Minor defect noticed by most

customersModerately high chance of detection

3Minor defect noticed by some

customers Low:High chance of detection

2Minor defect noticed by

discriminating customers

Relatively few failuresVery high chance of detection

1 No effect Remote: Failure is unlikely Almost certain detection

Detection is typically assumed to imply action can be taken

7-28


Investigate & Fix Special CausesFMEA Form - Initial Assessment

Process Step/Input

Potential Failure Mode Potential Failure EffectsSEV

Potential CausesOCC

Current ControlsDET

RPN

Actions Recommended

What is the process step/ Input under

investigation?

In what ways does the Key Input go wrong?

What is the impact on the Key Output Variables (Customer Requirements) or internal requirements?

How

Sev

ere

is th

e ef

fect

to th

e cu

sotm

er? What causes the Key Input to

go wrong?

How

ofte

n do

es c

ause

or

FM

occ

ur? What are the existing controls and

procedures (inspection and test) that prevent eith the cause or the Failure Mode? Should include an SOP number.

How

wel

l can

you

de

tect

cau

se o

r F

M? What are the actions

for reducing the occurrance of the

Cause, or improving detection? Should

have actions only on high RPN's or easy

fixes.

0

0

0

7-29


Investigate & Fix Special CausesFMEA Form - Long Term History

Current ControlsDET

RPN

Actions Recommended

Resp. Actions TakenSEV

OCC

DET

RPN

What are the existing controls and procedures (inspection and test) that prevent eith the cause or the Failure Mode? Should include an SOP number.

How

wel

l can

you

de

tect

cau

se o

r FM

? What are the actions for reducing the

occurrance of the Cause, or improving detection? Should

have actions only on high RPN's or easy

fixes.

Whose Responsible

for the recommended

action?

What are the completed actions taken with the

recalculated RPN? Be sure to include

completion month/year

0 0

0 0

0 0

0 0

7-30


Investigate & Fix Special CausesFMEA Methodology

Two major approaches: Starting with Cause & Effect Matrix Starting with FMEA directly from the Process Map

We will explain the approach using the C&E matrix, though both approaches are very similar

Spreadsheet tools have been prepared to assist you in the preparation of the FMEA

7-31


Investigate & Fix Special CausesFMEA Methodology - Starting with

C&E Matrix AdvantageAdvantage:: The Cause & Effect Matrix assists the

team in defining the important issues that the FMEA should address by helping to prioritize important customer requirements Process inputs that could potentially impact these

requirements Prioritizing the Key Process Inputs according to

their impact on the Output variables (We want to focus on Inputs that highly impact a large number of Outputs first

The C&E Matrix also provides quantitative output that can be used in the determination of the specific severity ratings for the next stage of the FMEA process

7-32


Investigate & Fix Special CausesFMEA - Step by Step

1. For each process input, determine the ways in which the input can go wrong (failure modes)

2. For each failure mode associated with the inputs, determine effects of the failures on the customer

Remember the internal customers! 3. Identify potential causes of each failure mode

4. List the Current Controls for each cause or failure mode

5. Create Severity, Occurrence, and Detection rating scales

6. Assign Severity, Occurrence and Detection ratings to each cause

7. Calculate RPN’s for each cause

8. Determine recommended actions to reduce high RPN’s

9. Take appropriate actions and recalculate RPN’s

7-33


Investigate & Fix Special CausesProcess Mapping Examples

ManufacturingManufacturing

Outputs Outputs

• TV of Mix -Quality Check around extrusion

• TV of Mix - Quality Check around extrusion

• Surface Area

• Pore Volume

• Appearance

• pH• Temp• Specific Gravity• Clarity

• Appearance (Color, Wetness)

• Appearance (Color)

• Physical Chemical Properties

• Cycle Time (plugging)

• Zone 3 Temp

Mixing

Water and Metals

Preparation

Extrusion

Extrude through die

Dryer Calciner

Material drying, surface

area issues

NADM

Solution Preparation

Impregnation

Metals addition

Fluid Bed DryerFinal

preparation / appearance

issues

Total Rate CMixer Speed CAl2O3 Qual URec Comp U

Ext Rate CDie Wear UExt RPMs CDie Change U

Temperature CRot speed CDraft CFeed Rate CDrying air U

Inputs Types Inputs Types

Nitric Acid CH2O2 CWater CADM CHold Time UAgitation C

Phos Acid CNozzle Type CSpray Time CWater CMoly CNickel CBase C

Temperature CRate CAir Flow CRes Time C

7-34



1. For Each Process Input, Determine the Ways in Which the Input Can Go Wrong (Failure Modes)

We will first deal with the Moly Flow Rate input variable.

Process Step/Input

Failure Modes - What can go

wrong? Effects CausesCurrent Controls

Impregnation/Moly Flowrate

Moly Flowrate is too high

Moly Flowrate is too low

FMEA Step 1

7-35



2. For Each Failure Mode Associated with the Inputs, Determine Effects

These effects are internal requirements for the next process and/or to the final customer

Process Step/Input



Impregnation/ Moly Flowrate


Off-Spec Material

Plugs dryer


Off-Spec Material

FMEA Step 2

7-36



3. Identify Potential Causes of Each Failure Mode

In most cases, there will be more than one Cause for a Failure Mode but we’ll keep it simple for this exercise

Process Step/Input





Off-Spec Material Weigh Cell Failure

Plugs dryer Weigh Cell Failure

Plugs dryer Operator Error


Off-Spec Material Weigh Cell Failure

Off-Spec Material Operator Error

May elect to list both effects on a single line since they relate to a single cause, and reduce a line in the table.

FMEA Step 3

7-37



4. List the Current Controls for Each Cause

Process Step/Input





Off-Spec Material Weigh Cell FailureDCS Program/Lab

Verification

Plugs dryer Weigh Cell FailureDCS Program/Lab

Verification

Plugs dryer Operator ErrorDCS Program/Lab

Verification


Off-Spec Material Weigh Cell FailureDCS Program/Lab

Verification

Off-Spec Material Operator ErrorDCS Program/Lab

Verification

For each failure mode/cause we list how we are either preventingpreventing the cause or detectingdetecting the failure mode

We will list the procedure number where we have a SOP

We need to be considerate of “holes” in the current controls column…..in this example, there are controls on the operation

FMEA Step 4

7-38



5. Create Severity, Occurrence, and Detection Rating Scales

Example Rating Scale

Rating Severity of Effect Likelihood of Occurrence Ability to Detect

10 Hazardous without warningVery high:

Can not detect

9 Hazardous with warningFailure is almost inevitable

Very remote chance of detection

8 Loss of primary functionHigh:

Remote chance of detection

7Reduced primary function

performance

Repeated failuresVery low chance of detection

6 Loss of secondary functionModerate:

Low chance of detection

5Reduced secondary function

performance

Occasional failuresModerate chance of detection

4Minor defect noticed by most

customersModerately high chance of detection

3Minor defect noticed by some

customers Low:High chance of detection

2Minor defect noticed by

discriminating customers

Relatively few failuresVery high chance of detection

1 No effect Remote: Failure is unlikely Almost certain detection

FMEA Step 5

7-39



6. Assign Severity, Occurrence and Detection Ratings to Each Cause

We are now ready to transfer the worksheet input to the FMEA form

Copy and paste the worksheet columns into the appropriate FMEA form columns

The team then starts scoring each row to compute the RPN values

Notes: You will only use one Severity value Determine which effect has the highest associated Severity and

use that SEV value for ALLALL causes for the related failure mode (Worst Case)

o When combining effects that have the same cause … Next Slide

FMEA Step 6

7-40


Investigate & Fix Special CausesRPN Review

Once you calculate the RPN for each failure mode / cause / controls combination, review the results and look for insights Do the gut check - does the Pareto of items make

sense? If not, maybe the ratings given are varying

Determine potential next steps: Data collection Experiments Process improvements Process control implementations

7-41


Investigate & Fix Special CausesApproaches to FMEA

Approach One (C&E Matrix Focus)Approach One (C&E Matrix Focus) Start with key inputs with the highest scores from the C&E

Matrix analysis Fill out the FMEA worksheet for those Inputs Calculate RPN’s and develop recommended actions for the

highest RPN’s Complete the Process FMEA for other Inputs over time

Approach Two (Customer Focused)Approach Two (Customer Focused) Fill out the failure mode and effects columns of the worksheet.

Copy to FMEA form and rate Severity. For High Severity Ratings, List causes and rate Occurrence

for each Cause For the highest Severity * Occurrence Ratings, evaluate

current controls For Highest RPN’s develop recommended actions

7-42


Investigate & Fix Special CausesApproaches to FMEA Continued…

Approach Three (Comprehensive)Approach Three (Comprehensive) Good approach for small processes Fill out the FMEA worksheet beginning with the

first process step and ending with the last Score SEV, OCC and DET for all causes Develop recommended actions for highest RPN’s

Approach Four (Super Focused)Approach Four (Super Focused) Pick the top Pareto defect item (Damaged

Components) or Failure Mode (Variability in Temperature)

Focus the FMEA process on only that defect or failure mode

Purpose: To “kill” that failure mode

7-43


Investigate & Fix Special CausesS.C.A.P. Considerations

1) A single joint is above UCL or below LCL2) A run of 8 above or below CL

Target

Time

2) Chronic Problems

Bad

BetterTime

1) Sporadic Problems

Note: S.C.A.P. may need to be specific to the type of instability

7-44



Special Cause DetectedBy Production ControlChart

DoesControl Strategy

Direct Investigating forSpecial Cause in

Laboratory?

Retest Sample

TestResults

Confirmed? Is RangeBetween Test Results

Less Than3.7M?

MeasurementProcess Stable?

(AccuracyMonitoring)

Report Initial TestResult To Production

Check for Special Causein Production Process

No

Yes

Yes

Was DataRecordedCorrectly?

Notify Productionof Lab Problem

Notify Productionof Lab Problem

Find and CorrectSpecial Cause inMeasurement Process(Precision Monitoring)

Find and CorrectSpecial Cause inMeasurement Process(Accuracy Monitoring)

Correct Error

Discard OriginalTest Results

Discard OriginalTest Results

Report CorrectedResults to Production

Retest Sample

Retest Sample

No

No

NoYes

Yes

Measurement System Investigation

7-45


Investigate & Fix Special CausesKnowledge/Systems Requirements

for a S.C.A.P.Compensating Action

• Criteria for judging if compensating action is appropriate.• What process variable is to be adjusted?• Required effect of process variable adjustment.• Amount of adjustment to obtain the required effect.• Criteria for judging if stability has been restored.

Investigative Action• Standard (Required) Process Operating Conditions.• Equipment failures signals.• Raw material analysis techniques.• Well-defined procedures.

Corrective Action• Well-defined procedures for correcting any deviation detected in the Investigative Action.• “Last Resort” adjustment procedures.• Criteria for judging if stability has been restored.

Documentation•Procedures/Systems for documenting actions, results and additional observations.• Procedures, Lists, charts for accumulating actions, results and additional observations.

7-46



• Control Charts provide information, I.e., when to take action and when not to take action.

• People must know what action to take. Actions need to be standardized for all people.

• People control the process, not the control charts.

• Investigation of Assignable Causes and the correction/ prevention of problems should never end.

• Control Charts and the S.C.A.P. need to be reviewed periodically and updated as needed.

• Process Control is the responsibility of Operations. Control Charts need to be in the hands of the people who control the process.

S.C.A.P.

7-47



Statistical Process Control

Use SPC to Maintain Current Process

Collect & Interpret

Data

Select Measures

Define Process

IsProcessCapable

?

Improve Process

Capability

IsProcessStable

?

Investigate & Fix

Special Causes

No

Yes

No

Yes

Statistical Process Control (SPC)

is a collection of activities:•Selection of appropriate process

measures•Collection of process data•Graphical analysis of data•Analysis of process stability•Use of data to investigate and

fix special causes in a continuous improvement cycle

7-1 Investigate & Fix Special Causes The Quality Improvement Model Use SPC to Maintain Current Process Collect & Interpret Data Select Measures Define.

Documents

fix special causes purpose

current process

process inputs

process capability

true causes

unstable measurement

improvement process

undesirable process